1. Field of the Invention
Disconnect or power stop mechanism adapted to de-clutch the driving and driven members of a refrigerant compressor in the event of an unsafe temperature condition, caused, for example, by loss of refrigerant from the system.
2. Summary of the Invention
This invention relates generally to drive means for a refrigerant compressor or the like and more particularly to means for disconnecting the compressor drive shaft from the driving pulley, or other type of drive means, in the event the compressor should become overheated, such as by loss of refrigerant or otherwise.
In the typical air conditioning system designed for use in an automotive application, an electromagnetic clutch is interposed between the drive pulley, which is driven from the automobile engine off one of the accessory drive belts, and the compressor drive shaft. The clutch is actuated and deactuated in response to a signal such as one derived from the air temperature within the automotive passenger compartment, or the fin temperature of the evaporator. This type of system has a number of disadvantages in that when the clutch is engaged it causes immediate drag on the engine which is particularly annoying at idle conditions since it may cause the engine to stall unless the idle is properly adjusted.
One improvement on the clutch actuated system described above is a system in which the capacity of the compressor is modulated from virtually zero to fully capacity over a continuous range of compressor output. In this case, the clutch can be eliminated and the compressor driven at all times while the engine is running.
When the compressor is driven continuously, it can be severely damaged when insufficient lubricant is present in the system or if the system should lose a substantial portion of its refrigerant charge. In the absence of some protective mechanism, the compressor will then overheat, possibly causing seizure of the moving parts.
In the present invention, means are provided for disconnecting or de-clutching the driving and driven members of the compressor if the compressor should reach an unsafe operating temperature. The system is designed so that the compressor may not be repaired on the spot by an inexperienced owner or operator; but will most likely be returned for service by a qualified mechanic who will be able to identify the cause of the overheating condition and reassemble the drive mechanism so that the compressor may be operated safely after the cause of the overheating is remedied.
More specifically, this takes the form of a disconnect mechanism including a temperature responsive actuator which causes a series of drive pins to disengage and permit the drive pulley member to free-wheel on a bearing surface on the shaft.